Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86/EFI changes from Peter Anvin:

 - Improve the initrd handling in the EFI boot stub by allowing forward
   slashes in the pathname - from Chun-Yi Lee.

 - Cleanup code duplication in the EFI mixed kernel/firmware code - from
   Satoru Takeuchi.

 - efivarfs bug fixes for more strict filename validation, with lots of
   input from Al Viro.

* 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, efi: remove duplicate code in setup_arch() by using, efi_is_native()
  efivarfs: guid part of filenames are case-insensitive
  efivarfs: Validate filenames much more aggressively
  efivarfs: Use sizeof() instead of magic number
  x86, efi: Allow slash in file path of initrd

1 files changed, 138 insertions, 8 deletions

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index fed08b661711..7320bf891706 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -79,6 +79,7 @@
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/pstore.h>
+#include <linux/ctype.h>
 
 #include <linux/fs.h>
 #include <linux/ramfs.h>
@@ -908,6 +909,48 @@ static struct inode *efivarfs_get_inode(struct super_block *sb,
         return inode;
 }
 
+/*
+ * Return true if 'str' is a valid efivarfs filename of the form,
+ *
+ *      VariableName-12345678-1234-1234-1234-1234567891bc
+ */
+static bool efivarfs_valid_name(const char *str, int len)
+{
+        static const char dashes[GUID_LEN] = {
+                [8] = 1, [13] = 1, [18] = 1, [23] = 1
+        };
+        const char *s = str + len - GUID_LEN;
+        int i;
+
+        /*
+         * We need a GUID, plus at least one letter for the variable name,
+         * plus the '-' separator
+         */
+        if (len < GUID_LEN + 2)
+                return false;
+
+        /* GUID should be right after the first '-' */
+        if (s - 1 != strchr(str, '-'))
+                return false;
+
+        /*
+         * Validate that 's' is of the correct format, e.g.
+         *
+         *      12345678-1234-1234-1234-123456789abc
+         */
+        for (i = 0; i < GUID_LEN; i++) {
+                if (dashes[i]) {
+                        if (*s++ != '-')
+                                return false;
+                } else {
+                        if (!isxdigit(*s++))
+                                return false;
+                }
+        }
+
+        return true;
+}
+
 static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
 {
         guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]);
@@ -936,11 +979,7 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
         struct efivar_entry *var;
         int namelen, i = 0, err = 0;
 
-        /*
-         * We need a GUID, plus at least one letter for the variable name,
-         * plus the '-' separator
-         */
-        if (dentry->d_name.len < GUID_LEN + 2)
+        if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
                 return -EINVAL;
 
         inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
@@ -1012,6 +1051,84 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
         return -EINVAL;
 };
 
+/*
+ * Compare two efivarfs file names.
+ *
+ * An efivarfs filename is composed of two parts,
+ *
+ *      1. A case-sensitive variable name
+ *      2. A case-insensitive GUID
+ *
+ * So we need to perform a case-sensitive match on part 1 and a
+ * case-insensitive match on part 2.
+ */
+static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode,
+                              const struct dentry *dentry, const struct inode *inode,
+                              unsigned int len, const char *str,
+                              const struct qstr *name)
+{
+        int guid = len - GUID_LEN;
+
+        if (name->len != len)
+                return 1;
+
+        /* Case-sensitive compare for the variable name */
+        if (memcmp(str, name->name, guid))
+                return 1;
+
+        /* Case-insensitive compare for the GUID */
+        return strncasecmp(name->name + guid, str + guid, GUID_LEN);
+}
+
+static int efivarfs_d_hash(const struct dentry *dentry,
+                           const struct inode *inode, struct qstr *qstr)
+{
+        unsigned long hash = init_name_hash();
+        const unsigned char *s = qstr->name;
+        unsigned int len = qstr->len;
+
+        if (!efivarfs_valid_name(s, len))
+                return -EINVAL;
+
+        while (len-- > GUID_LEN)
+                hash = partial_name_hash(*s++, hash);
+
+        /* GUID is case-insensitive. */
+        while (len--)
+                hash = partial_name_hash(tolower(*s++), hash);
+
+        qstr->hash = end_name_hash(hash);
+        return 0;
+}
+
+/*
+ * Retaining negative dentries for an in-memory filesystem just wastes
+ * memory and lookup time: arrange for them to be deleted immediately.
+ */
+static int efivarfs_delete_dentry(const struct dentry *dentry)
+{
+        return 1;
+}
+
+static struct dentry_operations efivarfs_d_ops = {
+        .d_compare = efivarfs_d_compare,
+        .d_hash = efivarfs_d_hash,
+        .d_delete = efivarfs_delete_dentry,
+};
+
+static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
+{
+        struct qstr q;
+
+        q.name = name;
+        q.len = strlen(name);
+
+        if (efivarfs_d_hash(NULL, NULL, &q))
+                return NULL;
+
+        return d_alloc(parent, &q);
+}
+
 static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 {
         struct inode *inode = NULL;
@@ -1027,6 +1144,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
         sb->s_magic             = EFIVARFS_MAGIC;
         sb->s_op                = &efivarfs_ops;
+        sb->s_d_op              = &efivarfs_d_ops;
         sb->s_time_gran         = 1;
 
         inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
@@ -1067,7 +1185,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
                 if (!inode)
                         goto fail_name;
 
-                dentry = d_alloc_name(root, name);
+                dentry = efivarfs_alloc_dentry(root, name);
                 if (!dentry)
                         goto fail_inode;
 
@@ -1084,7 +1202,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 
                 mutex_lock(&inode->i_mutex);
                 inode->i_private = entry;
-                i_size_write(inode, size+4);
+                i_size_write(inode, size + sizeof(entry->var.Attributes));
                 mutex_unlock(&inode->i_mutex);
                 d_add(dentry, inode);
         }
@@ -1117,8 +1235,20 @@ static struct file_system_type efivarfs_type = {
         .kill_sb = efivarfs_kill_sb,
 };
 
+/*
+ * Handle negative dentry.
+ */
+static struct dentry *efivarfs_lookup(struct inode *dir, struct dentry *dentry,
+                                      unsigned int flags)
+{
+        if (dentry->d_name.len > NAME_MAX)
+                return ERR_PTR(-ENAMETOOLONG);
+        d_add(dentry, NULL);
+        return NULL;
+}
+
 static const struct inode_operations efivarfs_dir_inode_operations = {
-        .lookup = simple_lookup,
+        .lookup = efivarfs_lookup,
         .unlink = efivarfs_unlink,
         .create = efivarfs_create,
 };